A conventional radio receiver device digitally processes a received radio signal of radio frequency by converting the received radio signal into a corresponding digital signal and demodulating the same.
In a radio receiver device disclosed in U.S. Pat. No. 6,952,573 (JP 2007-506363A), an analog circuit section for processing radio signals of radio frequencies and a digital circuit section for processing digital signals are provided closely to each other. In such a configuration, digital noise generated in the digital circuit section is transmitted to the analog circuit section. As a result, its receiver sensitivity (sensitivity of receiving radio signals) and hence the signal-to-noise (S/N) ratio are lowered.
In a radio receiver device disclosed in JP 2001-159673, a GPS satellite signal of intermediate frequency is generated from a received GPS satellite signal of radio frequency, and GPS data is acquired by demodulating the GPS satellite signal. During the GPS signal generation and the GPS data acquisition are under progress, digital calculation of GPS data by a digital calculation section is stopped. As a result, generation of noise from the digital calculation section is reduced so that the sensitivity of receiving the GPS signal is not so much reduced by the digital noise.
Even if the above digital calculation is performed, the digital calculation section may not generate noise or may generate only a limited amount of noise. In this instance, the sensitivity of receiving the GPS satellite signal will not be lowered so much. Therefore, if the digital calculation processing by the digital calculation section is stopped in such an instance, the amount of digital calculation processing of the digital calculation section will be necessarily reduced, resulting in lowered processing efficiency.